Metal cutting system for effective coolant delivery

ABSTRACT

A metal cutting system with a tool holder, a shim, an insert with a top depression, a top piece and a clamp. A rake face cooling channel for fluid delivery is formed between the top piece and the depression in the insert. A primary discharge slot at the end of the rake face cooling channel delivers fluid from below the cutting edge of the insert. A second cooling channel for delivery of fluid to the flank face is formed between the insert and the shim or is formed between the shim and the tool holder with a portion of the cooling channel passing through the shim.

CROSS-REFERENCE TO EARLIER PATENT APPLICATION

This patent application is a divisional patent application of co-pendingU.S. patent application Ser. No. 11/654,918 filed Jan. 18, 2007 for aMETAL CUTTING SYSTEM FOR EFFECTIVE COOLANT DELIVERY by Paul D. Prichard,Linn R. Andras and Ted Robert Massa. Applicants hereby claim the benefitof the priority filing date of said above-referenced parent patentapplication (i.e., U.S. Ser. No. 11/654,918 filed Jan. 18, 2007).Further, applicants hereby incorporate by reference herein the entiretyof said parent patent application (i.e., U.S. Ser. No. 11/654,918 filedJan. 18, 2007).

FIELD OF THE INVENTION

The subject invention is directed to metal cutting system and, inparticular, to a metal cutting system adapted to permit effectivecoolant delivery to an interface between a metal cutting tool and aworkpiece.

BACKGROUND OF THE INVENTION

Metal cutting tools for performing metal working operations generallycomprise a cutting insert having a surface terminating at a cutting edgeand a tool holder formed with a seat adapted to receive the insert. Thecutting insert engages a workpiece and removes a chip therefrom.Obviously, it is desirable to lengthen the life of a cutting insert inmetal cutting operations. Longer insert life leads to lower operatingcosts and better machine efficiency. One factor in the life of a cuttinginsert is the temperature of the insert during cutting operations. Ahigher insert temperature will result in a shorter useful life of aninsert.

Many systems have been designed to lower the insert temperature duringcutting. For example, coolants may be generally applied through nozzlesdirected at the cutting edge of the insert. The coolant serves not onlyto lower the temperature of the insert but also to remove the chip fromthe cutting area. The nozzles are often a distance of 1-12 inches awayfrom the cutting edge. This is too far of a distance for effectivecooling. The farther the coolant must be sprayed the more the coolantwill mix with air and the less likely it will be to actually contact thetool-chip interface. Some have improved cooling by directing highpressure and high volume coolant at the cutting edge as shown in U.S.Pat. No. 6,045,300 issued to Antoun. Others have designed groovesbetween the insert and a top plate that secures the insert in the holderto reduce the distance the coolant must be sprayed. This is shown inU.S. patent application serial number 2003/00820118 to Kraemer. Somehave delivered liquid nitrogen as the coolant relatively near thecutting edge of an insert as shown in U.S. Pat. No. 5,901,623 issued toHong. Each variation has shown limited effectiveness. Many still arepositioned to far from the tool-workpiece interface. Those with groovesbetween the top plate and the insert get fluid closer to thetool-workpiece interface but are not close enough. The design in Kraemeris also limited in that the direction of fluid flow is almost completelylimited to one plane. The liquid nitrogen system like that in Hong hasshown some benefit but is cost prohibitive for most applications. It isclear there remains a need for a simple and effective assembly forinsert cooling during metal cutting operations.

BRIEF SUMMARY OF THE INVENTION

The inventor(s) have recognized the problems associated withconventional cooling apparatus and have developed an insert assemblythat works with a conventional coolant system to deliver coolant to acutting insert that addresses the problems of the prior art.

In one embodiment of the invention, the assembly comprises a tool holderhaving a recess to accept a cutting insert and a passage for coolantdelivery; a shim having a cooling channel capable of delivering coolantto a flank face or cutting edge of an insert; a cutting insert having afrusto-conical depression in the center of the insert and an orificealigned with the coolant passage of the tool holder; a top piece with adepression in a top surface and a frusto-conical bottom aligned with thefrusto-conical depression of the cutting insert to form a fluid tightseal between the insert and top piece except for a rake face coolingchannel spanning from the insert orifice to a discharge slot that is inclose proximity to the cutting edge or corner of the insert; and a clampcapable of sealing the cooling channels and seating the cutting insertand top pieces. The oblique relationship between the top piece-insertinterface and the plane of the rake face of the insert enables coolantto be delivered from an angle below the plane of the rake face. In thisway the coolant impinges the underside of a chip. Delivery of coolant tothe flank of the insert combined with the rake face cooling describedherein has shown to be an efficient means of cooling the insert andremoving the chip. As a consequence insert life is significantlyimproved by using this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the present invention, as well as the advantagesderived therefrom, will become clear from the following detaileddescription made with reference to the drawings in which:

FIG. 1 is an exploded view of the invention with rake face cooling only;

FIG. 2 is an exploded view of the invention with rake and flank cooling;

FIG. 3 is a perspective view of the invention with rake face cooling andjets;

FIG. 4 is a perspective view of the preferred embodiment of theinvention with high volume flank cooling, rake face cooling and jets;

FIG. 5 is a cross section of a perspective view of the invention withrake and flank face cooling;

FIG. 6 is a cross section of a perspective view of the invention withrake and high volume flank face cooling;

FIG. 7 is a cross-sectional perspective of the invention engaging aworkpiece and forming a chip;

FIG. 8 is a cross section of a perspective view of the clamp and toppiece fixed together with a slotted spring pin;

FIG. 9 is a view of the insert side of the top piece with a centeringstud; and.

FIG. 10 is a perspective view of the centering stud.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1 of the invention, there is shown a tool holder 1having a recess 29 for receiving a cutting insert 10. The tool holder 1also has a coolant passage 2 for delivering fluid coolant to the recess29. An indexable, cutting insert 10 is positioned in the recess 29. Thecutting insert 10 has at least one flank face 12, a rake face 13 and abottom face 14. The intersection between the flank face 12 and the rakeface 13 forms a cutting edge 16. In the instance of a plurality of flankfaces, the intersection between two adjacent flank faces 12 and the rakeface 13 forms a cutting corner 17. It will be appreciated that a roundcutting insert does not include two adjacent flank faces and thereforedoes not include a cutting corner. Although a round cutting insert doesnot include a cutting corner it will be appreciated that in any case, acutting edge is present. An insert depression 15 is located in the rakeface 13 of the insert 10. The insert depression 15 is an area within therake face 13 that is lower than the remaining portion of the rake face13 surrounding the insert depression 15 and including the cutting edges16 and as appropriate, cutting corner 17. In one embodiment, the cuttingedges 16 and cutting cornerall lie within the same plane. It will beapparent that some of the cutting edges may also lie above or below oneanother in elevation. For example, this would be the case if anelliptically shaped insert with an uneven rake face were used as theinsert in the metal cutting system.

The insert 10 has an insert orifice 11 that aligns with the coolantpassage 2 of the tool holder 1 to receive coolant. The insert orifice 11opens to both the rake face 13 and the bottom face 14. A top piece 18 isadjacent to insert 10. The top piece 18 has a clamp side 20 and insertside 19. Insert side 19 of top piece 18 has a shape corresponding to theinsert depression 15 such that positioning the two together forms aseal. The top piece also has a reservoir 34 (shown in FIG. 5) in theinsert side 19. The reservoir 34 is a pocket in the insert side 19 ofthe top piece 18 that aligns with the insert orifice 11. The reservoir34 distributes coolant to the top piece 18. Top piece 18 also has atleast one rake face cooling channel 21. The rake face cooling channel 21is a groove formed in the insert side 19 of the top piece 18 that runsfrom the reservoir 34 to the point on the top piece 18 nearest thecutting edge 16 or cutting corner 17, as appropriate. See FIG. 5 for aview of the rake face cooling channel 21. When the top piece 18 isseated in the insert depression 15 the rake face cooling channel 21seals against the insert depression 15 to create a coolant path tocutting edge 16 or cutting corner 17. It is also contemplated that therake face cooling channel 21 could be formed by a groove in the insertdepression 15 which seals against the insert side 19 of the top piece18. A clamp 23 applies pressure to the top piece depression 22. Theclamp 23 maintains the alignment and seal between top piece 18, insert10 and tool holder 1. It will be appreciated that the type of clamp 23is not limited to the style shown in the drawings. Rather, the clamp 23can include any other suitable clamp style of a type well known in theart.

As shown in FIG. 7 when the insert 10 engages a workpiece 30 a chip 31is lifted away from the workpiece at the cutting edge 16 or cuttingcorner 17. The congruent relationship between the top piece 18 andinsert depression 15 creates a rake face coolant cooling channel 21 thatdirects coolant so that it is delivered from an angle below theintersection at the rake face 13 and the chip 31. This delivery anglecauses the coolant to impinge the underside of the chip resulting inimproved cooling and chip removal. The rake face cooling channel 21spans from the reservoir 34 to a point nearest the cutting edge. Aprimary discharge slot 27 is formed at the end of the rake face coolingchannel 21 nearest the cutting edge 16 or cutting corner 17. It is animportant aspect of this invention that the primary discharge slot 27lie below the cutting edge 16 or corner 17. In this description, “belowthe cutting edge” or “below the cutting corner” in this descriptionmeans generally towards the recess 29 as opposed to “above the cuttingedge” or “above the cutting corner” which would be generally towards theclamp. Cooling and chip removal are most efficient when the primarydischarge slot 27 is within about 0.100 inches of the chip.

In another embodiment shown in FIG. 2 and FIG. 5, a shim 3 having a topside 8 and a bottom side 36 is positioned between the tool holder 1 andthe insert 10. The shim 3 is oriented so that the bottom side 36 abutsthe tool holder 1 and the top side abuts the insert 10. A shim pin 6 isinserted through a shim pin hole 5 and a tool holder pin hole 7. Theshim pin 6 maintains the alignment of the shim 3 between the tool holder1 and insert 10. A shim orifice 4 is formed through the center of theshim 3. The shim orifice 4 provides a path for coolant to pass from thecoolant passage 2 of the tool holder 1 to the insert orifice 11. A slotforming a part of flank face cooling channel 9 is provided on the topside 8 of the shim 3. The insert bottom face 14 seals the exposed slotin the top side 8 of shim 3 to create a flank face cooling channel 9.The flank face cooling channel 9 spans from the shim orifice 4 almost toan outer portion of the shim 3 nearest the cutting edge 16 or cuttingcorner 17. The end of flank face cooling channel 9 nearest the cuttingedge has a curved base so that coolant is directed toward the cuttingedge 16 or cutting corner 17 or flank face 12 of the insert 10.

In the embodiment as shown, the insert 10 has flank faces 12 and flankedges 32 that taper inward at a shallow angle from the rake face 13 tothe bottom face 14. In this manner the width of shim 3 will be less thanthe width of the insert bottom face 14 and less than the width of therake face 13. Attention is drawn to the fact that this taper is meant toexpose the flank faces 12 and flank edge 16 to coolant. The tapering ofthe insert 10 allows a portion of the flank face cooling channel 9 to beexposed creating secondary discharge hole 28, thus enabling expulsion ofcoolant along the flank faces of the insert 10.

A third embodiment shown in FIG. 3 adds jets 33 to the top piece 18. Thejets 33 are additional coolant conduits to increase coolant flow rateand effectively direct more fluid to the tool-chip interface. The jets33 run from the reservoir 34 to a discharge point on the clamp side 20of the top piece 18 where the coolant can be directed at the tool-chipinterface.

An alternate embodiment of the invention is shown in FIG. 4 and FIG. 6.In this embodiment, the highest coolant flow rate is achieved providingflank and rake cooling. In this assembly, a shim 3 sits in the recess 29of tool holder 1 having a tool holder pin hole 7. The shim 3 has a shimorifice 4 and a shim pin hole 5. The shim pin 6 is threaded and extendsthorough the shim pin hole 5 in to the tool holder pin hole 7 which isalso threaded. This arrangement keeps the shim 3 aligned in relation tothe recess 29. A high volume flank cooling channel 35 is formed betweenthe tool holder 1 and shim 3. Part of the high volume flank coolingchannel 35 is formed by a groove in the bottom side 36 of the shim 3.This groove could also be formed in the recess 29 of the tool holder 1.The groove is closed by the recess 29 of the tool holder 1 creating apassage for coolant delivery. The high volume flank cooling channel 35extends partway along the interface between the tool holder 1 and theshim 3 starting at the shim orifice 4 then projects through the body ofthe shim 3 toward the flank face 12 or flank edge 32 of the insert 10ending with a secondary discharge hole 28 at a corner of the shim 3closest to the cutting edge 16 or cutting corner 17 of the insert 10.

The insert 10 has tapered flank faces 12 and flank edges 32 to allow foradequate coolant wash from the secondary discharge hole 28. An insertorifice 11 aligns with the shim orifice 4. The insert bottom face 14seats against the shim 3 to create a fluid tight seal. The insertdepression 15 is frusto-conical and mates to the insert side 19 of thetop piece 18 to create a fluid tight seal. The insert side 19 of the toppiece 18 is also frusto-conical. The reservoir is located in the centralportion of the insert side 19 and is in alignment with the insertorifice 11. The alignment of the reservoir 11, insert orifice 11, shimorifice 4 and coolant passage 2 creates a chamber from which coolant canfreely flow to the high volume flank coolant channel 35, rake facecooling channel 21 and jets 33. In a preferred embodiment, the rake facecooling channel 21 runs from the reservoir 34 to within about 0.100inches of the cutting edge 16 or cutting corner 17. At the end of therake face cooling channel 21 opposite the reservoir 34 there is a nib 42on the insert side 19 of the top piece 18. The nib 42 is a bumpprotruding from the insert side that interferes with the stream ofcoolant as it exits the primary discharge slot 27. A view of the nib 42is most clearly shown in FIG. 9. The nib 42 causes the coolant to sprayin a wide pattern from the primary discharge slot 27 as opposed to aless desirable concentrated stream that occurs without the nib 42. Therake face cooling channel is sized to be large enough to maximize flowwithout permitting entry of chips into the channel. Two jets 33 run fromthe reservoir 34 to exit points on the clamp side 20 that direct thecoolant towards the cutting edge 16 or cutting corner 17. A top piecedepression 22 is present on the clamp side 20. The clamp 23 has a clamphead 24 that engages the top piece depression 22 to seat the insert 10and maintain fluid tight seals of all the coolant ducts. In a preferredembodiment, a clamp screw 25 applies pressure to the clamp head 24 inthe direction of the top piece 18. A clamp pin 26 maintains alignment ofthe clamp head 24. It will be appreciated that although a specificclamping assembly is shown in the FIGS. 1-6 and 8, any suitable clampingassembly capable of holding the top piece, insert 10 and shim 3 securelyin the recess 29 will suffice. Many of these clamping assemblies arecommercially available and well known in the art.

In the preferred embodiment, the total flow of all coolant passagesshould not be less than 80% of the possible flow from an unrestrictedflood nozzle. It will be appreciated that some handling benefits havebeen seen when the top piece 18 is fixed to the clamp 23. Thisarrangement reduces the chance that an operator will inadvertently dropthe top piece when removing or installing the assembly. The mosteffective means of fixing the top piece 18 to the clamp 23 is with aslotted spring pin 39. The slotted spring pin 39 is inserted into aclamp bore 40 and a top piece bore 41 which are aligned as seen in FIG.8. Although other means of fastening the pieces together are possible,the use of a slotted spring pin 39 allows for some rotation of the toppiece 18 about the main axis of the slotted spring pin 39. Thisarrangement allows the top piece 18 to be aligned with the differingorientations of the insert 10.

A centering stud 43 can be included between the top piece 18 and insert10. The centering stud 43 seats into the reservoir 34 and extends intothe insert orifice 11. The shape of the centering stud conforms to theboundaries of the reservoir 34 and the insert orifice 11 and in this waythe centering stud 43 acts as an alignment device. The centering studhas an open interior so that coolant flow is not restricted. FIG. 9shows a centering stud fixed in the reservoir 34 of the top piece 18 andFIG. 10 is an isolated view of a centering stud. For illustrativepurposes, the insert 10 is not shown in FIG. 9.

The documents, patents and patent applications referred to herein arehereby incorporated by reference.

While the invention has been specifically described in connection withcertain specific embodiments thereof, it is to be understood that thisis by way of illustration and not of limitation, and the scope of theappended claims should be construed as broadly as the prior art willpermit.

1. A metal cutting system comprising: a tool holder having a recess and a coolant passage for delivery of fluids, a shim comprising a bottom side abutting the tool holder in the recess, a top side opposite the bottom side and a shim orifice aligned with the coolant passage and spanning from the bottom side to the top side, an insert having a rake face having an insert depression lower than the remainder of the rake face, at least two edges intersecting to form at least one cutting corner, an insert bottom face, at least one flank face being chamfered, at least one flank edge being chamfered in the same direction as the flank face, and an insert orifice spanning from the insert bottom face to the rake face, wherein the insert bottom face is superposed on the top side of the shim, a flank face cooling channel formed between the shim and the insert terminating with a secondary discharge hole directed at the cutting edge or flank face, wherein the flank face cooling channel is in communication with the coolant passage; a top piece including a clamp side and an insert side congruently shaped to fit in the insert depression and cooperatively forming a cooling channel between the top piece and insert depression for delivery of coolant to a cutting corner or a cutting edge, wherein the cooling channel is in communication with the coolant passage and a primary discharge slot to deliver coolant to the cutting corner, wherein the primary discharge slot is located below the at least one cutting corner; and a clamp to hold the insert and the shim securely in the tool holder.
 2. A metal cutting system according to claim 1, wherein the insert is indexable.
 3. A metal cutting system according to claim 1, wherein the primary discharge slot is within about 0.100 inches of the cutting corner.
 4. A metal cutting system according claim 1, wherein the top piece is fixed to the clamp.
 5. A metal cutting system according to claim 1, wherein the top piece further comprises a nib that projects from the insert side of the of the top piece and into the rake face cooling channel at a distal end of the rake face cooling channel opposite the insert orifice.
 6. The metal cutting system according to claim 1, wherein the tool holder further comprises a clamp screw hole and clamp pin hole, the top piece further comprises a top piece depression within the clamp side of the top piece, and the clamp further comprises a clamp head that engages the top piece depression, a clamp screw for attaching the clamp head to the tool holder and a clamp pin extended from the clamp head into the clamp pin hole to maintain alignment of the clamp head.
 7. The metal cutting system according to claim 6, wherein the tool holder further comprises a tool holder pin hole, and the shim further comprises a shim pin hole and shim pin which passes through the shim pin hole into the tool holder pin hole to maintain alignment of the shim with the tool holder. 